Skirted ball joint seal for a firearm drum



June 9, 195 9 c. 5. LA FEV R 2,889,654

SKIRTED BALL JOINT SEAL FOR A FIREARM DRUM Filed July 9, 1957 INVENTOR.

Clifford EHLTELFEVEI BY SKIRTED BALL JOINT SEAL FOR A a I DRUM Clifford E.. La Fever, Dearborn, assignor to the United States of America as represented by the Secretary of the Army Application July 9, 1957, Serial No. 670,834

' 4 Claims. (CI. 42-59 My invention relates to automatic guns having barrels and drums with chambers for inclosing cartridges for dis charge thereof and more particularly to gas seals for engagement between the chambers. and the barrels.

In conventional revolver-type guns the drums are pro: vided with cylindrical seals slidable in the chambers, responsive to gas pressure obtained through the discharge of the cartridges, to engage the barrel of the gun and prevent the escape of the gases into the clearance space between the drum and the barrel of the gun. In such guns a considerable quantity of gas leaked between the seals and the chambers to increase the heat of the drum.

During the life of conventional guns, the seals and the chambers are subject to considerable wear and thereby allow a greatly increased amount of gas to escape therebetween to further increase the heat of the drum.

When the number of rounds fired through such gJns was increased, it was found that thermal and dynamic reflection within the guns caused misalignment of the seals and the barrels and the discharge gases escaped therebetween to heat the drum to further increase the drum heat and it was found that the cartridges spontaneously discharged in the chambers.

It is an object of my invention to provide a seal disposed to compensate for any misalignment between the contacting surfaces of the seal and the barrel and to compensate for manufacturing tolerances.

Another object of my invention is to prevent the escape of the discharge gases into the clearance space between the chamber and the :barrel through the provision of a two-piece seal incorporating a rearwardly-disposed tubular member and a ring member forwardly thereof disposed for surface engagement with the rear face of the barrel.

A further object of my invention is to provide each seal with means on said tubular and ring members for forming a ball and socket engagement therebetween.

Other aims and objects of my invention will appear from the following description.

In carry out my invention, seals for the chambers are formed by the combination of a rearwardly-disposed tubular member and a ring members forwardly thereof, and the former is provided with a skirted rear portion arranged to contact the interior wall surfaces in the forward counterbored portion of each chamber and thereby decrease escape of the gases between the seals and the chambers. The tubular and ring members are disposed for ball and socket engagement therebetween, and the latter is disposed for obturative engagement of the forward face thereof with the rearward face of the barrel to prevent gas leakage therebetween.

With such seals installed in a gun the wear in the chambers and the seals was compensated for to such a degree that the heating of the drum showed no appre ciable increase during the life of the gun.

For a more complete understanding reference is directed to the following description and the accompanying drawing in which:

Fig. l is an elevational view of a gun incorporating my invention; and

Fig. 2 is an enlarged view similar to Fig. 1 with the seal in the position of obturation.

As shown in the drawings, gun 12 is provided with a recoil unit 14 having a rotatable shaft 19 therethrougha A drum 18 is fixedly mounted on shaft 19 and is pro An actuator 26 is disposed for axially slidable opera tion with respect to recoil unit 14 and for engagement with index rollers 24 for sequential rotation of chambers 20 into a firing station in axial alignment with barrel 16.

V The forward portion of each chamber 20 is provided Witha counterbored section 21 arranged to slidably receive the gas seal 28 of the present invention. Seal 28 is formed by a hollow tubular member 34 and a shorter ring memebr 32 forwardly adjacent thereto.

T ubular member 34 is provided with a central bore 50 substantially equivalent in diameter to the projectile 30 of cartridge 22. The exterior diameter of member 34 is slightly smaller than that of counterbored section 21 in order to produce a slidable fit therein for a purpose to be shown. The rear end of member 34 is cut away in a dishlike manner as shown at 36 to form a relatively thin-skirted portion capable of expanding into tight sealing contact with the interior wall surfaces of counterbored section 21. The forward end of member 34 is concavely formed as shown at 38 to provide a socketlike surface for matingly receiving the convexly formed rear end surface of ring member 32.

The forward end of ring member 32 is provided with an annular shoulder 46, and a washer 44 fixedly secured to drum shaft 19 projects in front of shoulder 46 to retain ring member 32 within counterbored section 21 in drum 18. The interior diameter of ring member 32 is slightly larger than the corresponding diameter of tubular member 34 in order to avoid interfering with the passage of projectile 30 therethrough in the event ring member 32 should be in a tilted position when in contact with the rear face of barrel 16.

Upon the firing of cartridge 22, the discharge gases expand into the skirted portion 36 at the rear end of tubular member 34 and force the thin walls thereof into gas sealing contact with the interior wall surfaces of counterbored section 21 while such member is being forced forwardly to move ring member 32 into gas sealing contact with the breech end of barrel 16.

While the ordinary gas seals utilized in revolver-type guns may operate satisfactorily when new, the repeated impacts of the seal on the breech face of the barrel and the erosive action of the powder gases released upon the discharge of the cartridges rapidly induce sufiicient Wear along the mating surfaces to completely destroy the required gas sealing fit therebetween. However, such is not the case where the gas seal of the present invention is utilized since the ball and socket engagement between tubular member 34 and ring member 32 permits the latter to tilt in any direction, as best shown in Fig. 2, to compensate for any wear on the forward face of member 32 or the breech face of barrel 16 and still maintain the required tight gas sealing contact therebetween. At the same time, the ball and socket engagement between members 32 and 34 effectively prevents the escape of any of the discharge gases therebetween during any tilting movement of ring member 32.

Thus, there is here provided a superior seal for preventing the escape of any of the discharge gases between the chamber and the barrel of a revolver-type gun even Patented June 9, 1959 after the mating surfaces of the seal and the barrel may have become worn or eroded.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1'. In a gun having a barrel, a revolving drum including ap'lurality of radially-disposed 'cartrid'gefiring chambers, and 'means for rotating the drum in response to the firing of the cartridges to sequentially bring each of the firing chambers into axial alignment with the barrel, the improvement of gas sealing means in the forward portion "of each of the firing chambers comprising a rearwardly-disposed slidable tubular member terminating in a socket portion at the forward end thereof, a ring member having a convexly formed rear end for mating engagement in said tubular member socket portion, said ring member being slidably disposed in the firing chamber between said tubular member and the breech face of the barrel whereby the forward movement imparted to said tubular member by the expansion of the discharge gases therebehind forces said ring member to tilt into gas sealing contact with the breech face of the 25 barrel.

2. The combination defined in claim 1 wherein the rear end of said tubular member is dished to provide an enlarged pressure area for receiving the thrust of the expanding discharge gases and also to form an annular thin-walled section adapted to be expanded into gas sealing contact with the interior wall surface of the firing chamber.

3. The combination defined in claim 1 wherein the inner periphery of said ring member is of greater diameter than the corresponding inner periphery of said tubular member to provide unobstructed passage of the projectile into the barrel despite a tilted position of said ring member.

4. The combination defined in claim 1 including means secured to the forward face of the drum for retaining said ring members within the firing chambers.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain Feb. 18, 1953 

